[PATCH v3 0/3] Enhancements to at91-sama5d2_adc driver

[PATCH v3 0/3] Enhancements to at91-sama5d2_adc driver

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

This is a rework of the first patches from
[PATCH 00/10] Enhancements to at91-sama5d2_adc and rtc trigger

I reworked according to Jonathan's review.
The RTC triggering part is still work in progress and I will send it separately

Changes in v3:
- Addressed feedback (each patch has changelog) from Jonathan on ML on the v2
of this series:
[PATCH v2 0/3] Enhancements to at91-sama5d2_adc driver

Eugen Hristev (3):
  iio: adc: at91-sama5d2_adc: fix differential channels in triggered
    mode
  iio: adc: at91-sama5d2_adc: handle unfinished conversions
  iio: adc: at91-sama5d2_adc: update for other trigger usage

 drivers/iio/adc/at91-sama5d2_adc.c | 167 ++++++++++++++++++++++++-------------
 1 file changed, 109 insertions(+), 58 deletions(-)

-- 
2.7.4

[PATCH v3 1/3] iio: adc: at91-sama5d2_adc: fix differential channels in triggered mode

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

The differential channels require writing the channel offset register (COR).
Otherwise they do not work in differential mode.
The configuration of COR is missing in triggered mode.

Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer support")
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v2:
- moved to the start of the list

 drivers/iio/adc/at91-sama5d2_adc.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index e1850f3..2a6950a 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -723,6 +723,7 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 
 	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
 		struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
+		u32 cor;
 
 		if (!chan)
 			continue;
@@ -732,6 +733,20 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 			continue;
 
 		if (state) {
+			cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
+
+			if (chan->differential)
+				cor |= (BIT(chan->channel) |
+					BIT(chan->channel2)) <<
+					AT91_SAMA5D2_COR_DIFF_OFFSET;
+			else
+				cor &= ~(BIT(chan->channel) <<
+				       AT91_SAMA5D2_COR_DIFF_OFFSET);
+
+			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+		}
+
+		if (state) {
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));
 			/* enable irq only if not using DMA */
-- 
2.7.4

[PATCH v3 2/3] iio: adc: at91-sama5d2_adc: handle unfinished conversions

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

It can happen that on IRQ trigger, not all conversions are done if
we are enabling multiple channels.
The IRQ is triggered on first EOC (end of channel), but it can happen
that not all channels are done. This leads into erroneous reports to
userspace (zero values or previous values).
To solve this, in trigger handler, check if the mask of done channels
is the same as the mask of active scan channels.
If it's the same, proceed and push to buffers. Otherwise, use usleep
to sleep until the conversion is done or we timeout.
Normally, it should happen that in a short time fashion, all channels are
ready, since the first IRQ triggered.
If a hardware fault happens (for example the clock suddently dissappears),
the handler will not be completed, in which case we do not report anything to
userspace anymore.
Also, change from using the EOC interrupts to DRDY interrupt.
This helps with the fact that not 'n' interrupt statuses are enabled,
each being able to trigger an interrupt, and instead only data ready
interrupt can wake up the CPU. Like this, when data is ready, check in
handler which and how many channels are done. While the DRDY is raised,
other IRQs cannot occur. Once the channel data is being read, we ack the
IRQ and finish the conversion.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v3:
- rewrite some code as suggested by Jonathan (w.r.t. state and dma enabled in
configure_trigger
- move back enable_irq in reenable_trigger : looks like it was a leftover,
thanks Jonathan

Changes in v2:
- move start of conversion to threaded irq, removed specific at91 pollfunc
- add timeout to channel mask readiness check in trigger handler
- use DRDY irq instead of EOC irqs.
- move enable irq after DRDY has been acked in reenable_trigger

 drivers/iio/adc/at91-sama5d2_adc.c | 62 +++++++++++++++++++++++++++++---------
 1 file changed, 48 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 2a6950a..49c2b9d 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -8,6 +8,7 @@
 
 #include <linux/bitops.h>
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/interrupt.h>
@@ -100,6 +101,8 @@
 #define AT91_SAMA5D2_IER_YRDY   BIT(21)
 /* Interrupt Enable Register - TS pressure measurement ready */
 #define AT91_SAMA5D2_IER_PRDY   BIT(22)
+/* Interrupt Enable Register - Data ready */
+#define AT91_SAMA5D2_IER_DRDY   BIT(24)
 /* Interrupt Enable Register - general overrun error */
 #define AT91_SAMA5D2_IER_GOVRE BIT(25)
 /* Interrupt Enable Register - Pen detect */
@@ -486,6 +489,21 @@ static inline int at91_adc_of_xlate(struct iio_dev *indio_dev,
 	return at91_adc_chan_xlate(indio_dev, iiospec->args[0]);
 }
 
+static unsigned int at91_adc_active_scan_mask_to_reg(struct iio_dev *indio_dev)
+{
+	u32 mask = 0;
+	u8 bit;
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->num_channels) {
+		struct iio_chan_spec const *chan =
+			 at91_adc_chan_get(indio_dev, bit);
+		mask |= BIT(chan->channel);
+	}
+
+	return mask & GENMASK(11, 0);
+}
+
 static void at91_adc_config_emr(struct at91_adc_state *st)
 {
 	/* configure the extended mode register */
@@ -746,25 +764,23 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
 		}
 
-		if (state) {
+		if (state)
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));
-			/* enable irq only if not using DMA */
-			if (!st->dma_st.dma_chan) {
-				at91_adc_writel(st, AT91_SAMA5D2_IER,
-						BIT(chan->channel));
-			}
-		} else {
-			/* disable irq only if not using DMA */
-			if (!st->dma_st.dma_chan) {
-				at91_adc_writel(st, AT91_SAMA5D2_IDR,
-						BIT(chan->channel));
-			}
+		else
 			at91_adc_writel(st, AT91_SAMA5D2_CHDR,
 					BIT(chan->channel));
-		}
 	}
 
+	/* Nothing to do if using DMA */
+	if (st->dma_st.dma_chan)
+		return 0;
+
+	if (state)
+		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
+	else
+		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
+
 	return 0;
 }
 
@@ -781,6 +797,7 @@ static int at91_adc_reenable_trigger(struct iio_trigger *trig)
 
 	/* Needed to ACK the DRDY interruption */
 	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+
 	return 0;
 }
 
@@ -1015,6 +1032,22 @@ static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
 	int i = 0;
 	int val;
 	u8 bit;
+	u32 mask = at91_adc_active_scan_mask_to_reg(indio_dev);
+	unsigned int timeout = 50;
+
+	/*
+	 * Check if the conversion is ready. If not, wait a little bit, and
+	 * in case of timeout exit with an error.
+	 */
+	while ((at91_adc_readl(st, AT91_SAMA5D2_ISR) & mask) != mask &&
+	       timeout) {
+		usleep_range(50, 100);
+		timeout--;
+	}
+
+	/* Cannot read data, not ready. Continue without reporting data */
+	if (!timeout)
+		return;
 
 	for_each_set_bit(bit, indio_dev->active_scan_mask,
 			 indio_dev->num_channels) {
@@ -1281,7 +1314,8 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 		status = at91_adc_readl(st, AT91_SAMA5D2_XPOSR);
 		status = at91_adc_readl(st, AT91_SAMA5D2_YPOSR);
 		status = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
-	} else if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+	} else if (iio_buffer_enabled(indio) &&
+		   (status & AT91_SAMA5D2_IER_DRDY)) {
 		/* triggered buffer without DMA */
 		disable_irq_nosync(irq);
 		iio_trigger_poll(indio->trig);
-- 
2.7.4

[PATCH v3 3/3] iio: adc: at91-sama5d2_adc: update for other trigger usage

[Eugen.Hristev]

From: Eugen Hristev <eugen.hristev@microchip.com>

This change will allow the at91-sama5d2_adc driver to use other triggers
than it's own.
In particular, tested with the sysfs trigger.
To be able to achieve this functionality, some changes were required:
1) Do not enable/disable channels when enabling/disabling the trigger.
This is because the trigger is enabled/disabled only for our trigger
(obviously). We need channels enabled/disabled regardless of what trigger is
being used.
2) Cope with DMA : DMA cannot be used when using another type of trigger.
Other triggers work through pollfunc, so we get polled anyway on every trigger.
Thus we have to obtain data at every trigger.
3) When to start conversion? The usual pollfunc (store time from subsystem)
would be in hard irq and this would be a good way, but current iio subsystem
recommends to have it in the threaded irq. Thus adding software start
code in this handler.
4) Buffer config: we need to setup buffer regardless of our own device's
trigger. We may get one attached later.
5) IRQ handling: we use our own device IRQ only if it's our own trigger
and we do not use DMA . If we use DMA, we use the DMA controller's IRQ.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v3:
- remove useless call to iio_triggered_buffer_predisable

Changes in v2:
- adapt to the situation of having the previous two patches ahead in the series

 drivers/iio/adc/at91-sama5d2_adc.c | 142 +++++++++++++++++++------------------
 1 file changed, 72 insertions(+), 70 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 49c2b9d..03ceab4 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -728,7 +728,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
 	struct at91_adc_state *st = iio_priv(indio);
 	u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
-	u8 bit;
 
 	/* clear TRGMOD */
 	status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
@@ -739,48 +738,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 	/* set/unset hw trigger */
 	at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
 
-	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
-		struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
-		u32 cor;
-
-		if (!chan)
-			continue;
-		/* these channel types cannot be handled by this trigger */
-		if (chan->type == IIO_POSITIONRELATIVE ||
-		    chan->type == IIO_PRESSURE)
-			continue;
-
-		if (state) {
-			cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
-
-			if (chan->differential)
-				cor |= (BIT(chan->channel) |
-					BIT(chan->channel2)) <<
-					AT91_SAMA5D2_COR_DIFF_OFFSET;
-			else
-				cor &= ~(BIT(chan->channel) <<
-				       AT91_SAMA5D2_COR_DIFF_OFFSET);
-
-			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
-		}
-
-		if (state)
-			at91_adc_writel(st, AT91_SAMA5D2_CHER,
-					BIT(chan->channel));
-		else
-			at91_adc_writel(st, AT91_SAMA5D2_CHDR,
-					BIT(chan->channel));
-	}
-
-	/* Nothing to do if using DMA */
-	if (st->dma_st.dma_chan)
-		return 0;
-
-	if (state)
-		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
-	else
-		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
-
 	return 0;
 }
 
@@ -905,9 +862,22 @@ static int at91_adc_dma_start(struct iio_dev *indio_dev)
 	return 0;
 }
 
+static bool at91_adc_buffer_check_use_irq(struct iio_dev *indio,
+					  struct at91_adc_state *st)
+{
+	/* if using DMA, we do not use our own IRQ (we use DMA-controller) */
+	if (st->dma_st.dma_chan)
+		return false;
+	/* if the trigger is not ours, then it has its own IRQ */
+	if (iio_trigger_validate_own_device(indio->trig, indio))
+		return false;
+	return true;
+}
+
 static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
 {
 	int ret;
+	u8 bit;
 	struct at91_adc_state *st = iio_priv(indio_dev);
 
 	/* check if we are enabling triggered buffer or the touchscreen */
@@ -928,6 +898,36 @@ static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
 		return ret;
 	}
 
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->num_channels) {
+		struct iio_chan_spec const *chan =
+					at91_adc_chan_get(indio_dev, bit);
+		u32 cor;
+
+		if (!chan)
+			continue;
+		/* these channel types cannot be handled by this trigger */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
+
+		cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
+
+		if (chan->differential)
+			cor |= (BIT(chan->channel) | BIT(chan->channel2)) <<
+				AT91_SAMA5D2_COR_DIFF_OFFSET;
+		else
+			cor &= ~(BIT(chan->channel) <<
+			       AT91_SAMA5D2_COR_DIFF_OFFSET);
+
+		at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+
+		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
+	}
+
+	if (at91_adc_buffer_check_use_irq(indio_dev, st))
+		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
+
 	return iio_triggered_buffer_postenable(indio_dev);
 }
 
@@ -948,21 +948,11 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
 		return -EINVAL;
 
-	/* continue with the triggered buffer */
-	ret = iio_triggered_buffer_predisable(indio_dev);
-	if (ret < 0)
-		dev_err(&indio_dev->dev, "buffer predisable failed\n");
-
-	if (!st->dma_st.dma_chan)
-		return ret;
-
-	/* if we are using DMA we must clear registers and end DMA */
-	dmaengine_terminate_sync(st->dma_st.dma_chan);
-
 	/*
-	 * For each enabled channel we must read the last converted value
+	 * For each enable channel we must disable it in hardware.
+	 * In the case of DMA, we must read the last converted value
 	 * to clear EOC status and not get a possible interrupt later.
-	 * This value is being read by DMA from LCDR anyway
+	 * This value is being read by DMA from LCDR anyway, so it's not lost.
 	 */
 	for_each_set_bit(bit, indio_dev->active_scan_mask,
 			 indio_dev->num_channels) {
@@ -975,12 +965,28 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 		if (chan->type == IIO_POSITIONRELATIVE ||
 		    chan->type == IIO_PRESSURE)
 			continue;
+
+		at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+
 		if (st->dma_st.dma_chan)
 			at91_adc_readl(st, chan->address);
 	}
 
+	if (at91_adc_buffer_check_use_irq(indio_dev, st))
+		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
+
 	/* read overflow register to clear possible overflow status */
 	at91_adc_readl(st, AT91_SAMA5D2_OVER);
+
+	/* continue with the triggered buffer */
+	ret = iio_triggered_buffer_predisable(indio_dev);
+	if (ret < 0)
+		dev_err(&indio_dev->dev, "buffer predisable failed\n");
+
+	/* if we are using DMA we must clear registers and end DMA */
+	if (st->dma_st.dma_chan)
+		dmaengine_terminate_sync(st->dma_st.dma_chan);
+
 	return ret;
 }
 
@@ -1135,6 +1141,13 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct at91_adc_state *st = iio_priv(indio_dev);
 
+	/*
+	 * If it's not our trigger, start a conversion now, as we are
+	 * actually polling the trigger now.
+	 */
+	if (iio_trigger_validate_own_device(indio_dev->trig, indio_dev))
+		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
 	if (st->dma_st.dma_chan)
 		at91_adc_trigger_handler_dma(indio_dev);
 	else
@@ -1147,20 +1160,9 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 
 static int at91_adc_buffer_init(struct iio_dev *indio)
 {
-	struct at91_adc_state *st = iio_priv(indio);
-
-	if (st->selected_trig->hw_trig) {
-		return devm_iio_triggered_buffer_setup(&indio->dev, indio,
-			&iio_pollfunc_store_time,
-			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
-	}
-	/*
-	 * we need to prepare the buffer ops in case we will get
-	 * another buffer attached (like a callback buffer for the touchscreen)
-	 */
-	indio->setup_ops = &at91_buffer_setup_ops;
-
-	return 0;
+	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
+		&iio_pollfunc_store_time,
+		&at91_adc_trigger_handler, &at91_buffer_setup_ops);
 }
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,
-- 
2.7.4

Re: [PATCH v3 1/3] iio: adc: at91-sama5d2_adc: fix differential channels in triggered mode

[Jonathan Cameron]

On Tue, 28 Jan 2020 12:57:39 +0000
<Eugen.Hristev@microchip.com> wrote:

> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> The differential channels require writing the channel offset register (COR).
> Otherwise they do not work in differential mode.
> The configuration of COR is missing in triggered mode.
> 
> Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer support")
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Applied to the fixes-togreg branch of iio.git.  Normally I avoid rebasing that
branch but I may do so this time given it's currently mid merge window.

The other two patches will have to wait for this one to get upstream of
my togreg branch which will take a few weeks.

Please give me a poke if I seem to have forgotten about them!

Thanks,

Jonathan

> ---
> Changes in v2:
> - moved to the start of the list
> 
>  drivers/iio/adc/at91-sama5d2_adc.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index e1850f3..2a6950a 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -723,6 +723,7 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  
>  	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
>  		struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
> +		u32 cor;
>  
>  		if (!chan)
>  			continue;
> @@ -732,6 +733,20 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  			continue;
>  
>  		if (state) {
> +			cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
> +
> +			if (chan->differential)
> +				cor |= (BIT(chan->channel) |
> +					BIT(chan->channel2)) <<
> +					AT91_SAMA5D2_COR_DIFF_OFFSET;
> +			else
> +				cor &= ~(BIT(chan->channel) <<
> +				       AT91_SAMA5D2_COR_DIFF_OFFSET);
> +
> +			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
> +		}
> +
> +		if (state) {
>  			at91_adc_writel(st, AT91_SAMA5D2_CHER,
>  					BIT(chan->channel));
>  			/* enable irq only if not using DMA */

Re: [PATCH v3 3/3] iio: adc: at91-sama5d2_adc: update for other trigger usage

[Jonathan Cameron]

On Tue, 28 Jan 2020 12:57:41 +0000
<Eugen.Hristev@microchip.com> wrote:

> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> This change will allow the at91-sama5d2_adc driver to use other triggers
> than it's own.
> In particular, tested with the sysfs trigger.
> To be able to achieve this functionality, some changes were required:
> 1) Do not enable/disable channels when enabling/disabling the trigger.
> This is because the trigger is enabled/disabled only for our trigger
> (obviously). We need channels enabled/disabled regardless of what trigger is
> being used.
> 2) Cope with DMA : DMA cannot be used when using another type of trigger.
> Other triggers work through pollfunc, so we get polled anyway on every trigger.
> Thus we have to obtain data at every trigger.
> 3) When to start conversion? The usual pollfunc (store time from subsystem)
> would be in hard irq and this would be a good way, but current iio subsystem
> recommends to have it in the threaded irq. Thus adding software start
> code in this handler.
> 4) Buffer config: we need to setup buffer regardless of our own device's
> trigger. We may get one attached later.
> 5) IRQ handling: we use our own device IRQ only if it's our own trigger
> and we do not use DMA . If we use DMA, we use the DMA controller's IRQ.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
If no one else comments by the time patch 1 is upstream of the togreg branch
then I'll apply 2 and 3.

Thanks,

Jonathan

> ---
> Changes in v3:
> - remove useless call to iio_triggered_buffer_predisable
> 
> Changes in v2:
> - adapt to the situation of having the previous two patches ahead in the series
> 
>  drivers/iio/adc/at91-sama5d2_adc.c | 142 +++++++++++++++++++------------------
>  1 file changed, 72 insertions(+), 70 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 49c2b9d..03ceab4 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -728,7 +728,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
>  	struct at91_adc_state *st = iio_priv(indio);
>  	u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
> -	u8 bit;
>  
>  	/* clear TRGMOD */
>  	status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
> @@ -739,48 +738,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  	/* set/unset hw trigger */
>  	at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
>  
> -	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> -		struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
> -		u32 cor;
> -
> -		if (!chan)
> -			continue;
> -		/* these channel types cannot be handled by this trigger */
> -		if (chan->type == IIO_POSITIONRELATIVE ||
> -		    chan->type == IIO_PRESSURE)
> -			continue;
> -
> -		if (state) {
> -			cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
> -
> -			if (chan->differential)
> -				cor |= (BIT(chan->channel) |
> -					BIT(chan->channel2)) <<
> -					AT91_SAMA5D2_COR_DIFF_OFFSET;
> -			else
> -				cor &= ~(BIT(chan->channel) <<
> -				       AT91_SAMA5D2_COR_DIFF_OFFSET);
> -
> -			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
> -		}
> -
> -		if (state)
> -			at91_adc_writel(st, AT91_SAMA5D2_CHER,
> -					BIT(chan->channel));
> -		else
> -			at91_adc_writel(st, AT91_SAMA5D2_CHDR,
> -					BIT(chan->channel));
> -	}
> -
> -	/* Nothing to do if using DMA */
> -	if (st->dma_st.dma_chan)
> -		return 0;
> -
> -	if (state)
> -		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
> -	else
> -		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
> -
>  	return 0;
>  }
>  
> @@ -905,9 +862,22 @@ static int at91_adc_dma_start(struct iio_dev *indio_dev)
>  	return 0;
>  }
>  
> +static bool at91_adc_buffer_check_use_irq(struct iio_dev *indio,
> +					  struct at91_adc_state *st)
> +{
> +	/* if using DMA, we do not use our own IRQ (we use DMA-controller) */
> +	if (st->dma_st.dma_chan)
> +		return false;
> +	/* if the trigger is not ours, then it has its own IRQ */
> +	if (iio_trigger_validate_own_device(indio->trig, indio))
> +		return false;
> +	return true;
> +}
> +
>  static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
>  {
>  	int ret;
> +	u8 bit;
>  	struct at91_adc_state *st = iio_priv(indio_dev);
>  
>  	/* check if we are enabling triggered buffer or the touchscreen */
> @@ -928,6 +898,36 @@ static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
>  		return ret;
>  	}
>  
> +	for_each_set_bit(bit, indio_dev->active_scan_mask,
> +			 indio_dev->num_channels) {
> +		struct iio_chan_spec const *chan =
> +					at91_adc_chan_get(indio_dev, bit);
> +		u32 cor;
> +
> +		if (!chan)
> +			continue;
> +		/* these channel types cannot be handled by this trigger */
> +		if (chan->type == IIO_POSITIONRELATIVE ||
> +		    chan->type == IIO_PRESSURE)
> +			continue;
> +
> +		cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
> +
> +		if (chan->differential)
> +			cor |= (BIT(chan->channel) | BIT(chan->channel2)) <<
> +				AT91_SAMA5D2_COR_DIFF_OFFSET;
> +		else
> +			cor &= ~(BIT(chan->channel) <<
> +			       AT91_SAMA5D2_COR_DIFF_OFFSET);
> +
> +		at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
> +
> +		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
> +	}
> +
> +	if (at91_adc_buffer_check_use_irq(indio_dev, st))
> +		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
> +
>  	return iio_triggered_buffer_postenable(indio_dev);
>  }
>  
> @@ -948,21 +948,11 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
>  	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
>  		return -EINVAL;
>  
> -	/* continue with the triggered buffer */
> -	ret = iio_triggered_buffer_predisable(indio_dev);
> -	if (ret < 0)
> -		dev_err(&indio_dev->dev, "buffer predisable failed\n");
> -
> -	if (!st->dma_st.dma_chan)
> -		return ret;
> -
> -	/* if we are using DMA we must clear registers and end DMA */
> -	dmaengine_terminate_sync(st->dma_st.dma_chan);
> -
>  	/*
> -	 * For each enabled channel we must read the last converted value
> +	 * For each enable channel we must disable it in hardware.
> +	 * In the case of DMA, we must read the last converted value
>  	 * to clear EOC status and not get a possible interrupt later.
> -	 * This value is being read by DMA from LCDR anyway
> +	 * This value is being read by DMA from LCDR anyway, so it's not lost.
>  	 */
>  	for_each_set_bit(bit, indio_dev->active_scan_mask,
>  			 indio_dev->num_channels) {
> @@ -975,12 +965,28 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
>  		if (chan->type == IIO_POSITIONRELATIVE ||
>  		    chan->type == IIO_PRESSURE)
>  			continue;
> +
> +		at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
> +
>  		if (st->dma_st.dma_chan)
>  			at91_adc_readl(st, chan->address);
>  	}
>  
> +	if (at91_adc_buffer_check_use_irq(indio_dev, st))
> +		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
> +
>  	/* read overflow register to clear possible overflow status */
>  	at91_adc_readl(st, AT91_SAMA5D2_OVER);
> +
> +	/* continue with the triggered buffer */
> +	ret = iio_triggered_buffer_predisable(indio_dev);
> +	if (ret < 0)
> +		dev_err(&indio_dev->dev, "buffer predisable failed\n");
> +
> +	/* if we are using DMA we must clear registers and end DMA */
> +	if (st->dma_st.dma_chan)
> +		dmaengine_terminate_sync(st->dma_st.dma_chan);
> +
>  	return ret;
>  }
>  
> @@ -1135,6 +1141,13 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>  	struct iio_dev *indio_dev = pf->indio_dev;
>  	struct at91_adc_state *st = iio_priv(indio_dev);
>  
> +	/*
> +	 * If it's not our trigger, start a conversion now, as we are
> +	 * actually polling the trigger now.
> +	 */
> +	if (iio_trigger_validate_own_device(indio_dev->trig, indio_dev))
> +		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
> +
>  	if (st->dma_st.dma_chan)
>  		at91_adc_trigger_handler_dma(indio_dev);
>  	else
> @@ -1147,20 +1160,9 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>  
>  static int at91_adc_buffer_init(struct iio_dev *indio)
>  {
> -	struct at91_adc_state *st = iio_priv(indio);
> -
> -	if (st->selected_trig->hw_trig) {
> -		return devm_iio_triggered_buffer_setup(&indio->dev, indio,
> -			&iio_pollfunc_store_time,
> -			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
> -	}
> -	/*
> -	 * we need to prepare the buffer ops in case we will get
> -	 * another buffer attached (like a callback buffer for the touchscreen)
> -	 */
> -	indio->setup_ops = &at91_buffer_setup_ops;
> -
> -	return 0;
> +	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
> +		&iio_pollfunc_store_time,
> +		&at91_adc_trigger_handler, &at91_buffer_setup_ops);
>  }
>  
>  static unsigned at91_adc_startup_time(unsigned startup_time_min,

Re: [PATCH v3 1/3] iio: adc: at91-sama5d2_adc: fix differential channels in triggered mode

[Eugen.Hristev]

On 02.02.2020 13:02, Jonathan Cameron wrote:
> On Tue, 28 Jan 2020 12:57:39 +0000
> <Eugen.Hristev@microchip.com> wrote:
> 
>> From: Eugen Hristev <eugen.hristev@microchip.com>
>>
>> The differential channels require writing the channel offset register (COR).
>> Otherwise they do not work in differential mode.
>> The configuration of COR is missing in triggered mode.
>>
>> Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer support")
>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> Applied to the fixes-togreg branch of iio.git.  Normally I avoid rebasing that
> branch but I may do so this time given it's currently mid merge window.
> 
> The other two patches will have to wait for this one to get upstream of
> my togreg branch which will take a few weeks.
> 
> Please give me a poke if I seem to have forgotten about them!
> 

Poke !

Eugen

> Thanks,
> 
> Jonathan
> 
>> ---
>> Changes in v2:
>> - moved to the start of the list
>>
>>   drivers/iio/adc/at91-sama5d2_adc.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
>> index e1850f3..2a6950a 100644
>> --- a/drivers/iio/adc/at91-sama5d2_adc.c
>> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
>> @@ -723,6 +723,7 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>>
>>        for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
>>                struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
>> +             u32 cor;
>>
>>                if (!chan)
>>                        continue;
>> @@ -732,6 +733,20 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>>                        continue;
>>
>>                if (state) {
>> +                     cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
>> +
>> +                     if (chan->differential)
>> +                             cor |= (BIT(chan->channel) |
>> +                                     BIT(chan->channel2)) <<
>> +                                     AT91_SAMA5D2_COR_DIFF_OFFSET;
>> +                     else
>> +                             cor &= ~(BIT(chan->channel) <<
>> +                                    AT91_SAMA5D2_COR_DIFF_OFFSET);
>> +
>> +                     at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
>> +             }
>> +
>> +             if (state) {
>>                        at91_adc_writel(st, AT91_SAMA5D2_CHER,
>>                                        BIT(chan->channel));
>>                        /* enable irq only if not using DMA */
> 

Re: [PATCH v3 1/3] iio: adc: at91-sama5d2_adc: fix differential channels in triggered mode

[Jonathan Cameron]

On Mon, 23 Mar 2020 10:42:19 +0000
<Eugen.Hristev@microchip.com> wrote:

> On 02.02.2020 13:02, Jonathan Cameron wrote:
> > On Tue, 28 Jan 2020 12:57:39 +0000
> > <Eugen.Hristev@microchip.com> wrote:
> >   
> >> From: Eugen Hristev <eugen.hristev@microchip.com>
> >>
> >> The differential channels require writing the channel offset register (COR).
> >> Otherwise they do not work in differential mode.
> >> The configuration of COR is missing in triggered mode.
> >>
> >> Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer support")
> >> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>  
> > Applied to the fixes-togreg branch of iio.git.  Normally I avoid rebasing that
> > branch but I may do so this time given it's currently mid merge window.
> > 
> > The other two patches will have to wait for this one to get upstream of
> > my togreg branch which will take a few weeks.
> > 
> > Please give me a poke if I seem to have forgotten about them!
> >   
> 
> Poke !
Timings have gone badly this cycle I'm afraid, so whilst it's made it
into staging/staging-next, I'm not going to be rebasing togreg
until after a pull request to Greg KH.  The timing issue was
I didn't get one out before staging most likely closed (one week
ahead of the window opening which it will probably do tomorrow).

So this will have to wait at least a few weeks more.

Sorry for the delay.

Jonathan

> 
> Eugen
> 
> > Thanks,
> > 
> > Jonathan
> >   
> >> ---
> >> Changes in v2:
> >> - moved to the start of the list
> >>
> >>   drivers/iio/adc/at91-sama5d2_adc.c | 15 +++++++++++++++
> >>   1 file changed, 15 insertions(+)
> >>
> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> >> index e1850f3..2a6950a 100644
> >> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> >> @@ -723,6 +723,7 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
> >>
> >>        for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> >>                struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
> >> +             u32 cor;
> >>
> >>                if (!chan)
> >>                        continue;
> >> @@ -732,6 +733,20 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
> >>                        continue;
> >>
> >>                if (state) {
> >> +                     cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
> >> +
> >> +                     if (chan->differential)
> >> +                             cor |= (BIT(chan->channel) |
> >> +                                     BIT(chan->channel2)) <<
> >> +                                     AT91_SAMA5D2_COR_DIFF_OFFSET;
> >> +                     else
> >> +                             cor &= ~(BIT(chan->channel) <<
> >> +                                    AT91_SAMA5D2_COR_DIFF_OFFSET);
> >> +
> >> +                     at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
> >> +             }
> >> +
> >> +             if (state) {
> >>                        at91_adc_writel(st, AT91_SAMA5D2_CHER,
> >>                                        BIT(chan->channel));
> >>                        /* enable irq only if not using DMA */  
> >   
> 

Re: [PATCH v3 2/3] iio: adc: at91-sama5d2_adc: handle unfinished conversions

[Jonathan Cameron]

On Tue, 28 Jan 2020 12:57:40 +0000
<Eugen.Hristev@microchip.com> wrote:

> From: Eugen Hristev <eugen.hristev@microchip.com>
> 
> It can happen that on IRQ trigger, not all conversions are done if
> we are enabling multiple channels.
> The IRQ is triggered on first EOC (end of channel), but it can happen
> that not all channels are done. This leads into erroneous reports to
> userspace (zero values or previous values).
> To solve this, in trigger handler, check if the mask of done channels
> is the same as the mask of active scan channels.
> If it's the same, proceed and push to buffers. Otherwise, use usleep
> to sleep until the conversion is done or we timeout.
> Normally, it should happen that in a short time fashion, all channels are
> ready, since the first IRQ triggered.
> If a hardware fault happens (for example the clock suddently dissappears),
> the handler will not be completed, in which case we do not report anything to
> userspace anymore.
> Also, change from using the EOC interrupts to DRDY interrupt.
> This helps with the fact that not 'n' interrupt statuses are enabled,
> each being able to trigger an interrupt, and instead only data ready
> interrupt can wake up the CPU. Like this, when data is ready, check in
> handler which and how many channels are done. While the DRDY is raised,
> other IRQs cannot occur. Once the channel data is being read, we ack the
> IRQ and finish the conversion.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

Applied this and patch 3 to the togreg branch of iio.git and pushed out as testing.

Thanks for reminding me about these.  Were still in the queue but I might
have forgotten to check this far back!

Jonathan

> ---
> Changes in v3:
> - rewrite some code as suggested by Jonathan (w.r.t. state and dma enabled in
> configure_trigger
> - move back enable_irq in reenable_trigger : looks like it was a leftover,
> thanks Jonathan
> 
> Changes in v2:
> - move start of conversion to threaded irq, removed specific at91 pollfunc
> - add timeout to channel mask readiness check in trigger handler
> - use DRDY irq instead of EOC irqs.
> - move enable irq after DRDY has been acked in reenable_trigger
> 
>  drivers/iio/adc/at91-sama5d2_adc.c | 62 +++++++++++++++++++++++++++++---------
>  1 file changed, 48 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 2a6950a..49c2b9d 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -8,6 +8,7 @@
>  
>  #include <linux/bitops.h>
>  #include <linux/clk.h>
> +#include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/dmaengine.h>
>  #include <linux/interrupt.h>
> @@ -100,6 +101,8 @@
>  #define AT91_SAMA5D2_IER_YRDY   BIT(21)
>  /* Interrupt Enable Register - TS pressure measurement ready */
>  #define AT91_SAMA5D2_IER_PRDY   BIT(22)
> +/* Interrupt Enable Register - Data ready */
> +#define AT91_SAMA5D2_IER_DRDY   BIT(24)
>  /* Interrupt Enable Register - general overrun error */
>  #define AT91_SAMA5D2_IER_GOVRE BIT(25)
>  /* Interrupt Enable Register - Pen detect */
> @@ -486,6 +489,21 @@ static inline int at91_adc_of_xlate(struct iio_dev *indio_dev,
>  	return at91_adc_chan_xlate(indio_dev, iiospec->args[0]);
>  }
>  
> +static unsigned int at91_adc_active_scan_mask_to_reg(struct iio_dev *indio_dev)
> +{
> +	u32 mask = 0;
> +	u8 bit;
> +
> +	for_each_set_bit(bit, indio_dev->active_scan_mask,
> +			 indio_dev->num_channels) {
> +		struct iio_chan_spec const *chan =
> +			 at91_adc_chan_get(indio_dev, bit);
> +		mask |= BIT(chan->channel);
> +	}
> +
> +	return mask & GENMASK(11, 0);
> +}
> +
>  static void at91_adc_config_emr(struct at91_adc_state *st)
>  {
>  	/* configure the extended mode register */
> @@ -746,25 +764,23 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
>  		}
>  
> -		if (state) {
> +		if (state)
>  			at91_adc_writel(st, AT91_SAMA5D2_CHER,
>  					BIT(chan->channel));
> -			/* enable irq only if not using DMA */
> -			if (!st->dma_st.dma_chan) {
> -				at91_adc_writel(st, AT91_SAMA5D2_IER,
> -						BIT(chan->channel));
> -			}
> -		} else {
> -			/* disable irq only if not using DMA */
> -			if (!st->dma_st.dma_chan) {
> -				at91_adc_writel(st, AT91_SAMA5D2_IDR,
> -						BIT(chan->channel));
> -			}
> +		else
>  			at91_adc_writel(st, AT91_SAMA5D2_CHDR,
>  					BIT(chan->channel));
> -		}
>  	}
>  
> +	/* Nothing to do if using DMA */
> +	if (st->dma_st.dma_chan)
> +		return 0;
> +
> +	if (state)
> +		at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
> +	else
> +		at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
> +
>  	return 0;
>  }
>  
> @@ -781,6 +797,7 @@ static int at91_adc_reenable_trigger(struct iio_trigger *trig)
>  
>  	/* Needed to ACK the DRDY interruption */
>  	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
> +
>  	return 0;
>  }
>  
> @@ -1015,6 +1032,22 @@ static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
>  	int i = 0;
>  	int val;
>  	u8 bit;
> +	u32 mask = at91_adc_active_scan_mask_to_reg(indio_dev);
> +	unsigned int timeout = 50;
> +
> +	/*
> +	 * Check if the conversion is ready. If not, wait a little bit, and
> +	 * in case of timeout exit with an error.
> +	 */
> +	while ((at91_adc_readl(st, AT91_SAMA5D2_ISR) & mask) != mask &&
> +	       timeout) {
> +		usleep_range(50, 100);
> +		timeout--;
> +	}
> +
> +	/* Cannot read data, not ready. Continue without reporting data */
> +	if (!timeout)
> +		return;
>  
>  	for_each_set_bit(bit, indio_dev->active_scan_mask,
>  			 indio_dev->num_channels) {
> @@ -1281,7 +1314,8 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
>  		status = at91_adc_readl(st, AT91_SAMA5D2_XPOSR);
>  		status = at91_adc_readl(st, AT91_SAMA5D2_YPOSR);
>  		status = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
> -	} else if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
> +	} else if (iio_buffer_enabled(indio) &&
> +		   (status & AT91_SAMA5D2_IER_DRDY)) {
>  		/* triggered buffer without DMA */
>  		disable_irq_nosync(irq);
>  		iio_trigger_poll(indio->trig);